1. Field of the Invention
This invention relates to an ion implanting apparatus and ion implanting method for implanting ions by irradiating a substrate (e.g. semiconductor substrate through the following description of the specification) with an ion beam. More particularly, the present invention relates to an ion implanting apparatus and an ion implanting method which can save energy for operating the ion implanting apparatus.
2. Description of the Related Art
In a related art ion implanting apparatus, in the period during which ion implantation is not executed for a substrate, e.g. in the period from when the ion implantation has been completed for a certain lot to when the ion implantation is started for a subsequent lot, the operating state of the apparatus was the following state (a) or (b). That is, the operation state (a) is to maintain in the same state as during the implantation except that the substrate is not irradiated with the ion beam while the ion beam of a required ion species is produced. The operation state (b) is to place in the state where almost all the devices constituting the ion implanting apparatus are stopped.
In recent years, the ion implanting apparatus has been also required to implement energy saving inclusive of reduction in power consumption as part of measure for environment protection. More widely speaking, the ion implanting apparatus has been required to implement not only power consumption but also reduction in the COO (Cost of Ownership: total maintenance cost relative to the operation and maintenance of the apparatus) such as raw gas consumption, exhaustion of devices, maintenance cost, etc.
However, since the operation state of (a) continues to produce the ion beam of the required ion species, not only wasteful power or raw gas for an ion source is consumed, but also exhaustion/deterioration of the ion source, a gas removal apparatus for removing harmful substances contained in exhaust gases and other devices is hastened to shorten their life. Therefore, reduction in COO cannot be implemented.
On the other hand, although the operation state of (b) can implement the reduction in COO, almost all the devices are stopped. Therefore, this method has a drawback that the start-up of the ion implanting apparatus is very slow when the ion implantation is resumed.
An object of this invention is to provide an ion implanting apparatus and an ion implanting method which can implement reduction in COO and make rapid start-up when implantation is resumed.
In order to accomplish the object above, the following means are adopted. According to the present invention, there is provided a first ion implanting apparatus comprising:
an ion source for ionizing a raw gas to produce a plasma and extracting an ion beam from the plasma;
a gas supplying device for supplying the raw gas to the ion source;
a plasma producing power source for supplying a power for producing the plasma to the ion source;
an energy separating magnet for selectively deriving ions having specific energy from the ion beam extracted from the ion source;
an energy separating magnet power source for supplying a power for energy separation to the energy separating magnet;
a scanning magnet for scanning the ion beam derived from the energy separating magnet;
a scanning magnet power source for supplying a power for scanning to the scanning magnet;
a beam paralleling magnet for parallel-scanning the ion beam derived from the scanning magnet so that it is in parallel to a reference axis;
a beam paralleling magnet power source for supplying a power for beam paralleling to the beam paralleling magnet;
an implanting chamber in which a substrate is irradiated with the ion beam derived from the beam paralleling magnet to implant ions into the substrate; and
a control device for controlling an operating state of the ion implanting apparatus in a period during which the ion implantation is not carried out for the substrate in a state in any mode selected from (a) a twilight mode in which a flow rate of the raw gas supplied from the gas supplying device to the ion source and the power supplied from the plasma producing power source to the ion source are reduced to values smaller than those when the ion implantation is carried out for the substrate and capable of keeping plasma production in the ion source; (b) a magnet-off mode in which the flow rate of the raw gas supplied from the gas supplying device to the ion source and the power supplied from the plasma producing power source to the ion source are reduced to values smaller than those when the ion implantation is carried out for the substrate and capable of keeping plasma production in the ion source, and outputs from the energy separating magnet power source, scanning magnet power source and beam paralleling magnet power source are stopped; and (c) a shut-down mode in which the supply of the raw gas from the gas supplying device to the ion source is stopped and outputs from the power sources are stopped.
The above-mentioned first ion implanting apparatus, preferably, further comprising:
an ion beam extracting power source for applying a voltage for extracting the ion beam to the ion source;
a mass separating magnet for selectively deriving ions having a specific mass number and valence from the ion beam extracted from the ion source;
a mass separating magnet power source for supplying a power for mass separation to the mass separating magnet;
an accelerating tube for accelerating or decelerating the ion beam derived from the mass separating magnet; and
an accelerating power source for applying a voltage for acceleration or deceleration to the accelerating tube,
wherein in the shut-down mode (c), outputs from the ion beam extracting power source, the mass separating magnet power source and the accelerating power source are stopped.
In accordance with above configuration, the operating state of the ion implanting apparatus in a period during which the ion implantation is not carried out for the substrate can be controlled in the state in any mode selected from the above (a) twilight mode, (b) magnet-off mode and (c) shut-down mode.
The twilight mode provides the smallest reduction quantity of COO among the three modes, but can still reduce the COO relative to the consumption of at least the raw gas and the power of the plasma producing power source. In addition, this mode can keep the plasma producing state in the ion source, and hence is the most rapid in the start-up of the apparatus in resuming the implantation.
The shut-down mode, which supply of the raw gas and almost all the main power sources are stopped, is the slowest in the start-up of the apparatus in resuming the implantation among the three modes, but is the most advantageous to the reduction of COO.
The magnet-off mode, which is an intermediate mode between the twilight mode and shut-down mode, is intermediate between both modes in the reduction quantity of COO and start-up speed of the apparatus.
As described above, in accordance with this ion implanting apparatus, the operating state of the apparatus in a period during which the ion implantation is not carried out for the substrate can be controlled in the state in any mode selected from the above three modes according to the request from a user. Therefore, the reduction of COO can be made and the start-up of the apparatus can be quickened.
Further, according to the present invention, there is also provided a second ion implanting apparatus comprising:
an ion source for ionizing a raw gas to produce a plasma and extracting the ion beam from the plasma;
a gas supplying device for supplying the raw gas to the ion source;
a main pump and a roughing pump for vacuum evacuating an interior of a beam line vacuum chamber which is connected to the ion source and through which the ion beam passes;
an implanting chamber in which a substrate is irradiated with the ion beam extracted from the ion source to implant ions into the substrate;
a vacuum preliminary chamber in which the substrate is taken in and out between the implanting chamber and an external atmosphere;
a vacuum preliminary chamber pump for vacuum evacuating an interior of the vacuum preliminary chamber; and
a control device for executing at least one of (a) a roughing pump low-speed mode in which the roughing pump is controlled to operate at a revolving speed lower than a steady revolving speed under conditions that the interior of the beam line vacuum chamber is in a predetermined high vacuum state and the raw gas is not supplied from the gas supplying device to the ion source; and (b) a vacuum preliminary chamber pump low-speed mode in which the vacuum preliminary chamber pump is controlled to operate at the revolving speed lower than the steady revolving speed when an interior of the vacuum preliminary chamber has reached a predetermined vacuum degree.
As in this ion implanting apparatus, by operating at least one of the roughing pump and vacuum preliminary chamber pump at the revolving speed lower than a steady revolving speed under a predetermined condition, the COO mainly relative to the power consumption for operating the vacuum pumps can be reduced. In addition, the operation of the vacuum pump is not stopped so that the pump can quickly restore to the steady revolving speed when necessary. Thus, the start-up of the apparatus when the implantation processing is resumed can be quickened.
A control device having both functions described above of the first and the second ion implanting apparatus may be provided.